Method of alkylation



July 6, 1943. McAFEE r 2,323,616

METHOD OF ALKYLATION Filed June 26, 1941 FF I I INVENTORS W ATTORNEY Patented July 6, 1943 METHOD or ALKYLATION Almer M. McAfee and Edward E. Dunlay, Port Arthur, Tex., assignors to Gull Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Application June 26, 1941, Serial No. 399,882

8 Claims.

This invention relates to a method of alkylation; and it comprises a method of alkylating paramns with olei'lns, wherein a normally gaseous paraffln is contacted with a normally gaseous olefin in the presence of a catalyst consisting essentially of an aluminum halide and a phenol all as more fully hereinafter set forth and as claimed.

Processes of converting normally gaseous hydrocarbo'ns into superior grades of liquid motor fuels engage the attention of the industry today and are becoming increasingly important. One such process which is a promising method of converting normally gaseous hydrocarbons into high quality liquid aviation fuels and the like is the process of alkylating paramns, especially branched-chain or isoparafiins, with olefins.

For example, insobutane is alkylated with isobutylene, thereby producing branched-chain octanes and other valuable components of aviation fuels.

The reactions which occur during, and the products which result from, alkylating a paraflln with an olefin are complex. The primary reaction appears to be as follows:

However, other reactions such'as cracking, in-

teraction of the primary products 'of alkylation,

isomerization and polymerization occur with the result that a mixture of hydrocarbons is obtained, some of which are desired and others of which are undesired. In so far as such further reactions result in the formation of branched-chain paraflins boiling in the desired motor fuel range, they are not altogether undesirable. They may even be desirable in that they produce a blended fuel. However, certain of these further reactions result in the formation of unsaturated hydrocarbons and hydrocarbons which boil considerably above the desired motor fuel boiling range.

advantageous.

ventlon to alkylate isobutane with 'butylenes to produce greater quantities of branched-chain octanes and other low-boiling, branched-chain parafilns.

We have found that paraflinic hydrocarbons can be rapidly and conveniently alkylated with olefins to produce large yields of low boiling, saturated branched-chain hydrocarbons and minimum amounts of unsaturated and high boiling hydrocarbons by contacting a lower parafiln with a lower olefin in the presence of a catalyst consisting essentially of an aluminum halide and a phenol.

This procedure is advantageously carried out by contacting a normally gaseous olefin with a molecular excess of a normally gaseous paraflin in the liquid phase in the presence of a catalyst of the above mentioned type. Vigorous agitation of the reaction mixture and recirculation of part of the reaction product and of the catalyst are A superatmospheric pressure is advantageously used, but atmospheric and subatmospheric pressures may be used. Temperatures not largely in excess of room temperature are in most cases sufficient to carry out the reaction. Used catalyst may be withdrawn from time to time and a corresponding amount of fresh catalyst charged to the system.

The primary advantage of our invention is that the yield of saturated, low boiling hydrocarbons is greatly increased compared to such- Yield when aluminum halides alone are used. The product is much less unsaturated and contains less high boiling ends. It is particularly suitable for use as or' in high octane aviation gasoline. Further advantages lie in the fact that the catalysts used are liquid or easily liqueflable and hence are more easily handled than solid aluminum halides; that the catalysts are less volatile than the aluminum halides alone and hence can be used at higher temperatures without loss by volatilization; and that the catalysts are lon er lived than the aluminum halides alone. Less isobutylene in accordance with our invention, a reaction of the following type predominates:

(3H1 CI-Ha CH; H H CH:=CCH:+CIIa-?-CH3 CH:-C(|J |CH1 H 11, H CH: Isobutylene isobutanc 2,2,4-trirnethylpentane Another possibility is as follows:

([111: $1 13 CH: CH: CHFCCHi+CIl3(IICH: CH;(|3(IJCH;

' n on; on; Isobutylcnc lsobutane 2,2,3,3-tctramethyl butane Such low molecular weight, highly branched hydrocarbons as the octanes illustrated above are the most desirable type of alkylation product and the production of this type is enhanced by the method of our invention.

In forming the catalysts employed in the practice of our invention, an aluminum halide such as aluminum chloride or aluminum bromide is combined with any suitable phenol or mixture of phenols such as phenol itself, cresol, xylenol, naphthol, or commercial cresylic acid. Mere intermixture of the components by vigorous agitation is suflicient. Heat may be employed if necessary. The catalyst need not be preformed but may be formed in situ by feeding the components into an alkylation mixture; In a case where alkylaticn is diflicult, as when ethylene is used as the olefin, a substantial molecular excess of aluminum halide is advantageously used, whereas in a case where alkylation is easy, as when isobutylene is reacted with isobutane, a substantial molecular excess of phenol is advantageously used. Specifically, in the case of an aluminum chloride-phenol catalyst, proportions of about 0.5 to 1.0 mol of aluminum chloride per mol of phenol are advantageous in the alkylation of isobutane with the butylenes, whereas proportions of about 1.0 to 1.5 mols of aluminum chloride per mol of phenol are advantageous in the alkylation of isobutane with ethylene and propylene.

The accompanying diagrammatic drawing, which panies and forms a part of the specification, illustrates an advantageous embodiment of our invention:

Referring to the drawing, a gaseous or liquid mixture comprising isobutane and isobutylene in a molecular proportion not less than about 2 mols of isobutane per mol of butylene is introduced from a source not shown through a conduit l info a high speed contactor 2. This contactor is advantageously provided with means (not shown) for recirculation and for temperature control and is maintained under a pressure suificient to liquefy the reactants. Contactor 2 is also supplied through a conduit 3 with fresh quantities of an aluminum chloride-phenol catalyst and recycled catalyst as explained in more detail below.

Reaction product and catalyst are withdrawn from contactor 2 through a conduit 4 containing a pressure-reducing valve 5 and are introduced into a settling chamber 6 which is provided with a cone-shaped bottom section 1, a weir 8 and a sight gage 9. The heavier catalyst settles into cone section 1 and is withdrawn therefrom through a conduit Hi. The major part of the catalyst thus withdrawn is pumped by a pump ll through conduit 3 back into contactor 2. Make-up catalyst from a source not shown is introduced as needed through a conduit. l2 into conduit 3 and thus into contactor 2. A small portion of the catalyst withdrawn from cone section 1 is withdrawn from the system through the conduit l3. By properly regulating the amount of used catalyst withdrawn through conduit I 3 and the amount of fresh catalyst introduced through conduit I2, the catalyst activity may be maintained constant and at any desired level.

Unreacted gases and vaporized reaction product rise from settling chamber 6 through a fractionating column I5. Normally liquid constituents are condensed therein and refluxed to chamher 6, while normall gaseous constituents pass out the top of the column through a conduit l6.

Liquid reaction product separated from catalyst overflows weir 8 in chamber 6. It is then pumped by a pump H through a conduit l8 into a fractionating column 19. The liquid level in chamber 6 is regulated with the aid of sight gage 9. In fractionating column IS, the reaction product is separated into a distillate consisting of a highly saturated aviation grade, high octane gas oline having an end point (A, S. T. M.) not above about 165 C., which i withdrawn through a conduit 20, and a higher boiling residue, which is withdrawn through a conduit 2|.

A certain amount of higher boiling residue is formed in any alkylation process, including that of the present invention, but the amount thereof produced by the process of our invention is small and is considerably less than would be produced with aluminum chloride or aluminum bromide alone.

The following specific example will serve further to illustrate the method and practice of our invention:

A C4 cut of a refinery cracking gas, containing about 22 per cent isobutane, 3 per cent n-butane, '71 per cent butylenes and 4 per cent C3 hydrocarbons, was introduced into a vessel containing an equimolecular complex of aluminum chloride and cresol kept suspended by agitation in a relatively heavy oil. At intervals hydrogen chloride gas was also introduced. The temperature of the reaction mixture was maintained at about 130 F. and the pressure at atmospheric. The gas was passed in for a period of 144 hours and unabsorbed gas was removed through a condensing and scrubbing system which separated condensable matter. The condensate thus removed from the efliuent gases was redistilled in a fractionating column. The distillate consisted of 2 parts by volume each of a very light gasoline (552 A. P. I. gravity and an A. S. T, M. endpoint of only 121 C.) and a somewhat heavier aviation grade distillate (51.4 A. P. I. gravity, an A. S. T. M. endpoint of 142 C. and an octane number above by the A. S. T. M.-C. F. R. method). Only one part by volume of higher boiling distillation residue remained.

The above example illustrates the effectiveness of our procedure even under conditions which are extremely favorable to olefin polymerization and the production of large amounts of high boiling oil. The molecular ratio of olefin to iso-parafiin in the feed gas was over 3 to 1, a condition which would be expected to result in the formation of a predominantly high boiling product instead of a predominantly low boiling product.

By taking other precautions, such as the maintenance of a molecular excess of iso-parafiin over olefin in the feed, and by recirculation of a large part of the reaction product including unused reactants, the yield of saturated, low boiling gasoline can be further increased. Also, by maintaining a pressure suflicient to liquefy the reactants the importance of an oil as suspending medium for the catalyst is reduced.

' In our copending application Serial No. 390,376, filed April 25, 1941, we have described and claimed a process of making superior grades of gasoline and other fuels for internal combustion engines from cracking gases and the like, wherein such a gas is reacted with a petroleum oil, preferably an aromatic or naphthenic petroleum oil, in the presence of an aluminum halide catalyst. The

oil appears to serve the double purpose of reducing polymerization of the gaseous olefins and of entering into the reaction itself.

The present invention provides a further method of reducing polymerization and other undesired reactions. As such it may be combined with or replace the method of said prior copending application or other methods of reducing polymerization and the like, to the end of increasing the amount of saturated, low boiling product. Thus by employing the procedure of the present invention, a lower ratio of paraflin to olefin may safely be used than may be used when an aluminum halide alone is used.

While our invention has been described with particular reference to certain embodiments and specific examples, it is not limited to such embodiments and examples except as defined in the appended claims.

What we claim is:

l. A method of alkylating normally gaseous iso-paraflins with normalll gaseous olefins comprising contacting a normally. gaseous iso-parafiin with a normally gaseous olefin in the presence of a catalyst consisting essentially of an aluminum halide anda phenol.

2. A method of alkylating normally gaseous iso-parafiins with normally gaseous olefins comprising contacting a normally gaseous iso-paraflln with a normally gaseous olefin in the presence of a catalyst consisting essentially of aluminum chloride and a phenol.

3. A method of alkylating normally gaseous iso-parafiins with normally gaseous olefins comprising contacting a normally gaseous iso-parafiln with a normally gaseous olefin in the presence of a catalyst consisting essentially of aluminum bromide and a phenol.

4. A method of producing saturated high octane gasoline comprising contacting a normally gaseous olefin with a molecular excess of a normally gaseous iso-parafiinin the presence of a catalyst consisting essentially of aluminum chloride and a phenol, separating catalyst from the reaction product, fractionally distilling the separated reaction product, and separating from the reaction product a fraction consisting of saturated high octane gasoline.

5. A method of alkylating isobutane with a butylene comprising contacting a. butylene with a molecular excess of isobutane in the presence of a catalyst consisting essentially of aluminum chloride and a phenol in the proportions of about 0.5 to 1.0 mol of aluminum chloride per mol of phenol. v

6. A method of alkylating'isobutane with olefins containing not more than three carbon atoms per molecule, comprising contacting isobutane with an olefin containing not more than three carbon atoms per molecule in the presence of a catalyst consisting essentially of aluminum chloride and a phenol in the proportions of about 1.0 to 1.5 mols of aluminum chloride per mol of phenol.

'7. The method of claim 1 wherein the catalyst consists essentially of aluminum chloride and phenol.

8. The-method of claim 1 wherein thecatalvst consists essentially of aluminum chloride and a cresol.

ALMER M. McAFEE. EDWARD E. DUNLAY. 

